I'm a bit confused about the OwnCloud licensing model. OwnCloud is an AGPL licensed product (at least the open source version is). Does that mean that the only license I can use for an OwnCloud app I write using the API would be AGPL as well?

The way I understand it, the AGPL license is so restrictive that no app can be written without it having to be released under the AGPL, which would include custom apps for customers who don't want to spend a small fortune on the OwnCloud Enterprise edition. Somehow that feels wrong, so I might have gotten it all wrong and would be happy if somebody with a clear understanding of this topic could shed some light on this.

To me, this sounds not-so-wrong. You still will be able to charge the customer for your work, it will just be available to anyone after the fact. But you could market even that, by advertising your experience in the field.
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MarcelJun 17 '13 at 11:34

2 Answers
2

The AGPL version 3 is compatible with the GPL version 3 and the LGPL version 3 is also compatible to GPL version 3. That being said you can publish the app under the AGPL v3, the GPL v3 or other compatible licenses.

These licenses allow you to sell the app but the buyer is allowed to publish the app for free. That is the goal of the General Public Licenses. The licensed software is and will always be free software and all software that use parts of it will always be free software.

But you do not need to sign a contributer agreement of OwnCloud as that is only required if you want to contribute to the core.

IANAL and this is not a legal advice. Furthermore the copyright laws and exceptions differs from country to country.

In US the API cannot be copyrighted. Therefore technically if you use the API you can use any licence you want for your application. I don't know about any interpretation in this respect in other parts of world.

However even if you distribute your application separately it might have an effect on the joined product. Depending on how the "work as a whole" is interpreted if it is server side the joined work might be binding on AGPL or it cannot be run. So you may need a licence which is compatible with AGPL and is 'upgraded' to AGPL. So while the source code is theoretically on weaker licence you de-facto use AGPL (unless user have implementation of API on another license). This is similar to definition of 'derived work' discussion with GPL and I am not aware of any binding interpretation one way or another.

If your application is not joined with server (communicates by network) my interpretation (after very quick look on AGPL) is that it can be on any license.

PS. As others pointed out you are allowed to charge for application on AGPL.